High-speed printer with selectively operable print hammer

ABSTRACT

A high-speed printer wherein the type-carrying member is provided with staggered rows of projections on the reverse side of each type character, and wherein a plurality of hammers operating at a print position selectively cooperate with the projections of a respective row.

[ 1 March 6, 1973 United States Patent 11 1 Niccolai HIGH-SPEED PRINTERWITH 3,128,693 4/1964 Thiemann...........................

SELECTIVELY OPERABLE PRINT I? gy s--- en urg et a HAMMER 3,220,343 II/1965 Wasserman..... [75] Inventor: Adrlano Nlccolai, Cornaredo3,331,316 7 7 BrettimWMm (Milan), 1ta1y 3,371,766 3/1968Sta11er............ 3,490,366 1/1970 Benson et a1. [73] Assignee:Honeywell lnformatmn Systems 3,542,182 11/1970 Lagenbergerm -p- Turm,Italy 3,575,107 4/1971 McDowell July 14, 1970 Primary Examiner-WilliamB. Penn 22 Filed:

211 App]. 190.; 54,814

AttorneyGeorge V. Eltgroth, Lewis P. Elbinger, Frank L. Neuhauser, OscarB. Waddell and Joseph B. Forman Foreign Application Priority Data July7, 1969 ltaly.............,.............l9699A/69 T C A R T S B A 7 5 411 MW mu. I4 w 0 we 91 .1 Lu C4 3 9 4 0 1m C Sh um 11 21 55 A high-speedprinter wherein the type-carrying [58] Field of Search member isprovided with staggered rows of projections on the reverse side of eachtype character, and wherein a plurality of hammers operating at a printReferences Cited UNITED STATES PATENTS 5/1960 l-lense..... 12/ 196 lposition selectively cooperate with the projections of a respective row.

...l0l/93 C Amada C 4 Claims, 6 Drawing Figures PATENTEUMR 6 3,719,139

' SHEET 10F 3 Adriano N/CCOLAI I X VE NTOR.

PATENTED 5 I975 SHEET 3 or 3 Adriana N CCOLAI IN"[ 10R HIGH-SPEEDPRINTER WITH SELECTIVELY OPERABLE PRINT HAMMER BACKGROUND OF THEINVENTION The present invention relates to highspeed impact printersused in data processing systems, and more particularly to printers ofthis type which are known as platen printers; i.e., printers which printby means of the impact of one or more printing members, or hammers,against a fixed printing surface, or platen.

In such printers, a type-carrying member consisting, for example, of aplurality of flexible type-carrying elements supported from a belt, isinterposed between hammer platen and is driven so that all of thecharacters forming the set of characters carried by the typecarryingmember are positioned in sequence in front of each print position.

One of the most serious problems encountered in these printers is thatof interference between print hammer and type-carrying member, which mayresult in jamming and breaking of the interfering members. This dangeris lessened if the type-carrying elements are suitably spaced apartalong the direction of motion, although such arrangement causes asubstantial reduction in the printing speed inasmuch as the velocity atwhich the type-carrying member can be driven is limited. I

Another partial solution to the problem, often employed, is that ofsuitably beveling the comers of the print hammer and the type-carryingelements to reduce the width of the striking surface in the direction ofmotion of the type-carrying elements.

Moreover, in some synchronous printers, the print hammer must have awidth sufficient to span two adjacent print positions, so that an evengreater spacing of the type-carrying elements is required to prevent twocharacters being printed at a time in a single printing operation.Therefore the printing speed of this latter printing device is evenfurther limited.

Therefore, it is the object of this invention to provide an improvedprinter which eliminates or greatly reduces some or all of theabove-mentioned limitations.

SUMMARY OF THE INVENTION According to the present invention, printing isprovided by means of a type-carrying member on which, at a single printposition, at least two print hammers act alternatively or selectivelyaccording to the character to be printed.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described withreference to the accompanying drawings, wherein:

FIG. 1 is a perspective view of a printer which employs the printingapparatus of the invention;

FIG. 2 is a cross-sectional view taken along a plane perpendicular tothe printing plane of a prior art printer;

FIG. 3 is a cross-sectional view taken along a plane perpendicular tothe printing plane of an embodiment of the invention;

FIG. 4 is a cross-sectional view taken along a plane perpendicular tothe printing plane of another embodiment of the invention;

FIG. 5 is a perspective view of a serial synchronous printer employingthe printing apparatus of the invention; and

FIG. 6 is a perspective view of an alternative printing apparatusaccording to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The printer of FIG. 1 is aparallel belt printer, of the platen type, employing the printingapparatus of the invention. However, the remarks made hereinafterrelative to the invention are applicable to other printer types, such asserial or parallel printers, chain, bar or ribbon printers, synchronousor asynchronous printers, and printers provided with a printing headeither stationary or moving along the print line. Only the elements ofthe printer needed for an understanding of the invention are shown,inasmuch as the basic structure of these printers are well-known tothose skilled in the art.

The type-carrying member is formed by an endless flexible belt 1provided with a set of elastic blades 2. Each one of blades 2 carries atits free end a graphic type character in relief, such as alphabeticletter, a numerical figure, or the like. The type-carrying member may bemade of a flexible steel strap. It is provided with a set of holes 3which are engaged by the teeth "of a driving wheel 4. Wheel 4 is rotatedby a motor means The type-carrying member is positioned for a suitablelength thereof a short distance away from a platen 6 against which aprint-receiving member 7 is resting. By virtue of the rotation ofdriving wheel 4, the characters located at the ends of blades 2 move inproximity to print-receiving member 7 along a hypothetical line, whichwill hereinafter be termed the print line. Along this print line, andinterposed between type-carrying blades 2 print-receiving member 7, isan inking ribbon 8, which for simplicity, is represented as a typewriterribbon. Practically, however, inking ribbons having a width equal to theentire length of the print line, and which move in a directionperpendicular to the length of the print line, are usually employed inparallel printers.

The print line is divided into hypothetical print positions, each suchprint position having a width equal to thedistance between adjacentprinted characters; i.e., usually one-tenth inch (2.54 mm.). Each printposition is provided with a pair of print hammers 9 and 10, which facethe print position and are arranged in two rows in two respectivelevels.

Type-carrying blades 2 move between the heads of print hammers 9 and 10and inking ribbon 8. Blades 2 are provided, on their reverse sides, withprojections 2a of suitable thickness, alternately arranged on twodifferent levels. In FIG. 1 only four hammers, correspond ing to twoadjacent print positions,are shown. By a technique well-known in theart, in order to permit the positioning of these hammers very closetogether, two of the four hammers are straight, and the other two arebent at right angles, thus permitting the alternate staggering of theelectromagnets which actuate the hammers.

In the parallel printer, an entire bank of such hammers is mounted alongthe length of the print line, whereas in a serial printer only twohammers, such as hammers 9 and 10, are required. In the latter instancethe hammers are mounted on a carriage movable along the print line, andapparatus is provided for shifting the hammers and the carriage alongthe print line through the various print positions. Composite techniquesare adopted for serial-parallel printers.

The two rows of print hammers cooperate respectively with the two rowsof projections 2a on the rear of the type-carrying blades. For eachprint position each hammer of the first row is adapted to print withhalf the set of characters located on alternate blades, and each hammerof the second row is adopted to print with the remaining half of thecharacters. As the electronic character identification equipmentprovided for these printers, well known to those skilled in the art,delivers information expressed in a binary code, the selectiveidentification of the corresponding hammer to be energized to print apredetermined character in a predetermined print position requires onlythe testing of one digit in the binary code. For example, a widely usedarrangement consists of using a generator of timing pulses, whichdelivers a pulse each time a character of the set is passing a printposition. These pulses are applied to a counter, which responds to yielda sequence of binary signals, each representing a serial number or acharacter code. This number, or code, is even or odd according to thevalue of its least significant bit. The value of this bit may thereforecontrol whether a hammer of the first or the second row is actuated.

Accordingly, the problem of possible interference between print hammersand type-carrying blades is solved, as explained in detail in FIGS. 2and 3.

In the prior art printer of FIG. 2 is shown a print hammer 11 and anumber of adjacent type-carrying blades 12, 13, 14, 15. For purposes ofexplanation, the set of type-carrying blades disposed along the printline will now be assumed to be a fixed reference system, andprint-receiving member 16, inking ribbon 17 and platen 18, as well asprint hammer 11, will be assumed to be moving in the sense of arrows Iand II relative to the reference system; however, in reality, it is thetypecarrying blades which are moving. This assumption permits of abetter clarification of the interference action, by providing for avector composition of the as sumed lateral displacement of the hammerand its real transverse motion when the hammer is driven against atype-carrying blade in the direction indicated by arrow III.

The dashed lines 19 and 20 represent the envelope of all regionsoccupied by the hammer cross-section during its forward and backwardmotion. From this envelope it is apparent that the left edge of blade 14interferes with hammer 11, as does the right edge of blade 12. Toobviate such problem, the prior art would provide for a greater distancebetween adjacent blades.

However, according to the instant invention, this greater spacingbetween type-carrying blades is not necessary, as is shown in FIG. 3,because the possibility of interference is eliminated by using bladesprovided with different projections on alternate rows. Thus, the printerof the instant invention comprises a set of typecarrying blades 21, 22,23, 24, 25 and a print hammer 26. Blades 21, 23, 25 have upperprojections 21a, 23a and 25a, through which the figure is sectioned, andblades 22 and 24 have lower projections 27 and 28.

When hammer 26 is driven against one of the blades with upperprojections, for example blade 23, to effectuate the printing operation,no interference is possible with the adjacent blades because of theample safety margin provided, inasmuch as such adjacent blades have noupper projection. When a character carried by a blade with a lowerprojection, such as blades 22 and 24 which are interposed between blades21, 23, and 25, a second print hammer, located at a lower level (FIG. 1)is actuated. This second hammer acts on the lower row of projectionsprovided on blades 22 and 24, shown by the solid lines 27 and 28.

It is evident that if a greater margin of safety against the danger ofinterference is desired, it is possible to use, in place of pairs ofhammers and two rows of staggered projections, a greater number ofhammers, for a print position for example three hammers, and acorresponding number of rows of staggered projections on thetype-carrying blades.

The principle of the invention also offers a substantial advantage inthe case of serial, and possibly parallel-serial, printers. In manyprinters of this type, the print hammer is moved along the print line ata uniform velocity, occupying the correct successive print positionsonly at predetermined moments. The printing usually occurs on-the-fly;i.e., at the time when the character to be printed is brought into thecorrect print position by virtue of the motion of the type-carryingmember. However, this time usually does not coincide with the moment atwhich also the print hammer is in the correct print position; instead,the hammer may be offset to the right or left of the correct position.This offset distance in extreme conditions, may be equal to an entirepitch of a print position.

In these circumstances, printers use a print hammer having a width equalto the width of two print positions. Accordingly, the print charactersand their related type-carrying members in prior art printers arecorrespondently spaced to avoid the printing of two adjacent charactersat the same time. However, according to the instant invention as shownin FIG. 4, more closely spaced adjacent characters, are provided eventhough the width of the print hammer 52 is nearly equal to the width oftwo print positions. As illustrated in FIG. 4, this is accomplished bythe use of a plurality of rows of staggered projections on the reversesides of the type-carrying members. Accordingly, with the same velocityof the type-carrying member, relative to the print-receiving member, andwith an equal number of characters, the printing speed is substantiallydoubled.

The preceding description and figures refer to a printer in which thetype-carrying member is formed of a set of flexible blades carried by,or forming a part of a flexible belt. However, the instant invention isalso applicable to printers having for type-carrying members a bar, aribbon, or a chain, or even a star-shaped or a cup-shaped member. Inparticular, FIG. 5 shows the pertinent features of a platen-type serialsynchronous printer, in which the type characters are distributed on atype-carrying star-shaped member, similar to the printer illustrated incopending U.S. Pat. application Ser. No. 50,659 filed June 29, 1970 inthe name of Sergio Cattaneo and assigned to the assignee of the presentinvention. This star-shaped member is maintainedin rotation by a motormeans M through a gear pair 31, a

rotating bar and a bevel gear 29. A 'worm screw 32, having a pitch equalto the print pitch, i.e., to the spacing between two adjacent printpositions, is also maintained in rotation motor means M.

A drive nut 33 is engaged by worm screw 32 and forms a part of acarriage 34, on which bevel gear 29 and the type-carrying star-shapedmember are mounted. Thus, for each turn of screw 32, carriage 34advances by a print pitch, and, since bevel gear 29 has a l 1 ratio, thetype-carrying star makes a complete revolution.

The printer is operated during the continuing motion of carriage 34,when the characters to be printed in sequence are in the correct printposition. Electronic identification and timing apparatus, not shown,provide for actuating print hammers 36 and 37 individually and at theproper time.

The width of hammers 36 and 37 nearly spans two adjacent printpositions, so that the desired character is printed in the correctposition regardless of the position reached by the carriage between thecorrect print position and the next print position one. To provide formaintaining a close spacing between adjacent type characters, thereverse side of each type-carrying blade is provided with a projectionof suitable thickness, such projections being alternately arranged intwo different rows to cooperate, respectively with one or the other ofhammers 36 and 37.

A variation of the invention, provides a printing device having a singlehammer. The striking head of this single hammer, in addition to beingmoved in the printing direction, is movable so as to selectively strikeone of the rows of projections of the type-carrying member. FIG. 6illustrates such an embodiment.

The print hammer 38 is joumalled to an arm 39, which in turn isjoumalled to a support. Under the combined action of an electromagnet 40and a return spring 41, arm 39 selectively assumes one of two stablepositions. Depending on the position of arm 39 the print hammer may beactuated to strike either the first or the second row of projections.

lclaim:

1. A high-speed printer of the platen type comprising a plurality oftype characters, a type carrying member disposed adjacent the printerplaten and having said type characters mounted thereon, said typecarrying member being movable to present each type character in sequencein front of a print position on the platen, each of said type charactersbeing provided with a single projection on its reverse side, saidprojections of all the type characters being distributed sequentiallyand repetitively over a plurality of projection rows and alternatelyarranged on different levels, a printing carriage movable alongsubsequent print positions, said carriage having a plurality of printhammers mounted thereon to provide at least one print hammer adjacenteach of said projection rows, each of said hammers having a widthsubstantially greater than the span of a single print position and nogreater than the span of two adjacent print positions, each of saidhammers being so disposed as to cooperate upon actuation thereof with arespective projection of a projection row to selectively strike theprojection corresponding to a type character to fili g-inc: of claim 1wherein each of said projections is disposed in two rows and whereinsaid plurality of print hammers comprises two print hammers, onedisposed above the other in alignment transverse to said projectionrows.

3. The printer of claim 1 wherein each of said hammers is of a widthsufficient to span substantially two print positions.

4. The printer of claim 1 wherein each of said projections is disposedin two rows and wherein each of said hammers is of a width sufficient tospan substantially two print positions, said plurality of print hammerscomprising two print hammers one disposed above the other in alignmenttransverse to said projection rows.

1. A high-speed printer of the platen type comprising a plurality oftype characters, a type carrying member disposed adjacent the printerplaten and having said type characters mounted thereon, said typecarrying member being movable to present each type character in sequencein front of a print position on the platen, each of said type charactersbeing provided with a single projection on its reverse side, saidprojections of all the type characters being distributed sequentiallyand repetitively over a plurality of projection rows and alternatelyarranged on different levels, a printing carriage movable alongsubsequent print positions, said carriage having a plurality of printhammers mounted thereon to provide at least one print hammer adjacenteach of said projection rows, each of said hammers having a widthsubstantially greater than the span of a single print position and nogreater than the span of two adjacent print positions, each of saidhammers being so disposed as to cooperate upon actuation thereof with arespective projection of a projection row to selectively strike theprojection corresponding to a type character to be printed.
 1. Ahigh-speed printer of the platen type comprising a plurality of typecharacters, a type carrying member disposed adjacent the printer platenand having said type characters mounted thereon, said type carryingmember being movable to present each type character in sequence in frontof a print position on the platen, each of said type characters beingprovided with a single projection on its reverse side, said projectionsof all the type characters being distributed sequentially andrepetitively over a plurality of projection rows and alternatelyarranged on different levels, a printing carriage movable alongsubsequent print positions, said carriage having a plurality of printhammers mounted thereon to provide at least one print hammer adjacenteach of said projection rows, each of said hammers having a widthsubstantially greater than the span of a single print position and nogreater than the span of two adjacent print positions, each of saidhammers being so disposed as to cooperate upon actuation thereof with arespective projection of a projection row to selectively strike theprojection corresponding to a type character to be printed.
 2. Theprinter of claim 1 wherein each of said projections is disposed in tworows and wherein said plurality of print hammers comprises two printhammers, one disposed above the other in alignment transverse to saidprojection rows.
 3. The printer of claim 1 wherein each of said hammersis of a width sufficient to span substantially two print positions.